This has been an excellent, interesting and informative thread
I've just read it from start to finish and really enjoyed it, particularly the old clippings and cuttings. I can't believe black orp hens averaged 212 eggs in 1930, I guess the profusion of feather now precludes that happening again. Thank you to all posters
In the UK, there are utility classes at either one or both of the 2 big national shows (can't remember).
I used to keep a few utility LF white sussex (originally from a 50 year closed flock) as well as ordinary LF red and white sussex. I kept them for fun and did not conduct laying trials or anything like that, so all observations are anecdotal. The utility hens were small in size (in between a 'normal' sussex bantam and LF) but the best would be extremely heavy for their size, the body weighty and compact, feathers sleek and close to the body. They would be passed over in a show class. The best ones would be extremely active on the range and food/growth conversion was excellent. However, even the best layers were no better than some of my other birds - sussex, orp/dotte cross, polands and even a couple of orps. Personally I don't find the flavour of Sussex remarkable, I'd rather eat something else. And actually in my view you get a better tasting egg from a poland!
I hadn't thought of utility keepers possibly being the ones to cause standards-writers to increase weights, food for thought.